Device for applying glue to the supporting belt of a screen printing screen

ABSTRACT

Device for applying a film of glue to a travelling belt of a screen printing machine, especially for textile fabric, said device comprising a roller contacting the belt along a genatrix on one side and dipping into a glue trough on the opposite side, further comprising a flexible doctor lying mainly parallel to said roller and having means to curve an adjustable length of both end parts towards said roller.

[ 1 June 6,1972

United States Patent Vertegaal [56] References Cited UNITED STATES PATENTS 154] DEVICE FOR APPLYING GLUE TO THE SUPPORTING BELT OF A SCREEN PRINTING SCREEN [72] Inventor:

ll8/DS 18/204 Lehman.............................l18/123 X 2,754,796 7/l956 Faulkner Ct Jacobus G. Vertegaal, Boxmeer, Nether- 3,104,182 1963 Schneider BK lands 8/1959 [73] Assignee: Stork Amsterdam N.V., Amstelveen, FOREIGN PATENTS OR APPLICATIONS Netherlands 583,575 9/1933 Germany.........................,......ll8/DS [22] Filed: Apr. 15, 1970 Primary ExaminerLouis K. Rimrodt Attorney-Irving M. Weiner [21] Appl. No.1

[57] ABSTRACT Device for applying a film of glue to a travelling belt of a [30] Foreign Application Priority Data May 2, 1969 Netherlands...................-.. I

' a screen printing machine, especially for textile fabric, said device comprising a roller contacting the belt along a genatrix on one side and dipping into a glue trough on the opposite side, further comprising a flexible doctor lying mainly parallel to said roller and having means to curve an adjustable length of both end parts towards said roller.

.118/123, 1is 204 ....B05c 1 1/04 1 18/204, 123

4 Claims, 2 Drawing figures DEVICE FOR APPLYING GLUE TO THE SUPPORTING BELT OF A SCREEN PRINTING SCREEN BRIEF DESCRIPTION OF THE PRIOR ART The invention relates to a device for applying glue to a supporting belt or printing blanket of a screen printing machine, comprising a glue roller with adjustable length-and a flexible doctor for wiping the excess glue from the supporting belt.

Such a glueing device is commonly known and serves to apply a band of glue on the supporting belt. Said band should have a breadth as large as the breadth of the web to be printed, e.g., textile. The web is temporarily secured to the belt by means of the glue before it is being printed, e.g., with screen stencils.

The glueing device may be constructed either as an individual displaceable unit, which canbe moved to under the supporting belt and which is secured in position at that location, or it may form a part of the screen printing machine itself.

It is obvious to arrange the doctor in such a manner that it is parallel to the glue roller, so that a proper contact between the doctor and the supporting belt on the one hand and between the glue roller and the supporting belt on the other hand is at any time possible.

The length of the glue roller should be adjustable (e.g., by interchanging the roller) to the breadth of the web to be printed.

Evidently either a doctor with the length of the glue roller or a doctor covering the full breadth of thesupporting belt may be used. I

A disadvantage of thelatter doctor is in that always a glue layer is applied over the full breadth of the supporting belt so that glue is present beside the web to be printed.

Attempts have been made to overcome this trouble by using a doctor with a length which is equal to the breadth of the glue roller and/or breadth of the web used at that moment.

The doctor should then be interchanged simultaneously with the glue roller. A disadvantage of the latter doctor is however that especially at high speeds of the supporting belt the excess glue which amasses behind the doctor flows out laterally and works itself around the free ends of the doctor, so that nevertheless a stripe of glue of disproportionate thickness is produced on the supporting belt beside the web to be printed. 7

Moreover it is difficult, on account of the special cross-sectional profile which the doctor should have for its fixation in a doctor holder arranged under the supporting belt, to replace the doctor each time when it is necessary to change over to another printing breadth.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a doctor mechanism for such a glueing device in which these disadvantages are avoided. According to the invention the glueing device comprises means for adjusting the desired length of the doctor and for turning the ends of the doctor towards the glue roller.

This feature is advantageous on the one hand in that the length of the active part of the doctor can be adjusted without dismounting and on the other hand in that on either side of the wiping portion of the doctor a part is formed, which is turned towards the glue roller. By these means the excess glue is positively prevented from running from-the one side of the doctor to the other side. It should be noted that the lateral parts of the doctor are lying under an angle with the middle portion, which stands at right angles with the direction of movement of the supporting belt. The ends of the doctor which are turned towards the glueing roller surely contact the belt and thus prevent the glue film from flowing out broadwise.

The glueing device according to the invention is advantageous in that, where comparatively small variations in width are concerned, even in operation, the width of the glue film can be corrected. When, for example, a glue film of 120 cm in width is required, a glue roller with a length of l 10 cm will suffice. Without the ends turned towards the glueing roller the glue film applied in the width of HO cm would become slowly larger owing to the fact that the glue flows laterally out until a width of about -140 cm is obtained. The equilibrium attained depends on the velocity of the supporting belt to be provided with glue; the greater the velocity the greater the width of the glue film.

A film of glue once applied cannot be removed by scraping off by means of the doctor. The minimal width of the film of glue is thus determined by the length of the glueing roller, whereas the maximal width is determined by the adjustment of the ends of the doctor turned towards the glueing roller, said ends preventing the excess glue from flowing out further along the doctor.

BRIEF SURVEY OF THE DRAWINGS FIG. 1 is a perspective view of a glueing device according to one embodiment of the invention; and

FIG. 2 gives an enlarged detail showing a perspective view of a part of the doctor holder with clamping member.

DESCRIPTION OF A PREFERRED EMBODIMENT With reference to FIG. 1 it should be noted that the glueing device comprises a frame 2 supported by wheels 1 in which a glue roller 3 with adjustable length is supported by rollers 4. The glue roller 3 is rotated by the supporting belt or printing blanket (not shown) and revolves thereby in a glue container 5 which is fed by means of a glue pipe 6. The frame 2 can travel by means of the wheels I on the rails 7 and is secured against displacement through the locking means 8. The fixed frame is provided with supports 9 in which the doctor holder 10 is secured. The level in the glue container 5 can be determined by means of the feeler 11. In a known manner a signal can be obtained from the feeler 11 bywhich means the supply of glue, via the pipe 6, to the glue container 5 can be regulated.

In the case as represented in the drawing the doctor 12 is of a T cross section and the doctor holder 10 is provided with a groove likewise of a T cross section.

The glueing device according to FIG. 1 operates in broad outlines as follows.

The frame 2 on the wheels 1 is moved to under the supporting belt of a screen printing machine, (not shown). The glue roller 3 presses on the one hand against the supporting belt and runs on the other hand through the glue bath. It is obvious that the glue roller delivers a certain quantity of glue to the supporting belt. Pressed against the supporting belt at some distance as contemplated in the direction of advance before the glue roller 3 'is the doctor 12 which via the doctor holder 10 and the supports 9 is connected with the fixed frame 2.

According to the invention the length of that portion of the doctor 12 which is parallel to the glue roller 3 is adjustable. Moreover the invention provides means to turn the end parts of the doctor 12 over an adjustable distance towards the glue roller 3. With reference to FIG. 2 it should be noted that for that purpose along the case-shaped doctor holder 10 the standing clamping ledge 13, which is turned towards the glue roller 3, is shortened at both ends. On the contrary, the clamping ledge 14 extends on the full length of the doctor holder 10. Slidable carriages 15 are provided around the doctor holder 10. These carriages are positioned at the ends of the holder 10 and can be easily slid along the doctor holder 10. By means of handles 16 and wing bolts 17 the carriages 15 can be locked on a stiffening beam 18 of the doctor holder 10. Each carriage 15 is provided with a clamping plate 19 which constitutes the clamping member proper according to the invention. The clamping plate 19 is arranged in such a manner that its longitudinal axis is parallel to the doctor holder 10. The plate 19 is provided with an inclined clamping slit (indicated by the arrows 20) into which fits the doctor 12.

It will be clear that by means of the clamping member 19 and due to the cooperation of the doctor holder and the carriage a part 12' of the doctor is laterally bent outwards on either side thereof. This part 12' on either side of the doctor 12 is turned towards the glue roller 3.

As depicted in FIG. 2 it is possible to secure the end of the part 12 of the doctor 12 to the carriage 15 by means of a bolt. In this manner a loop is formed, the advantage of which is in the fact that the band of glue supplied by the glue roller remains of a limited width and is prevented from becoming wider than permitted by the position of the loop.

FIG. 2 indicates for illustrative purposes by means of a dash line A the boundary of the band of glue applied on the supporting belt by the glueing roller, while the dash line B indicates the boundary of the band of glue widened by the doctor.

The band of glue is lying both before and behind the doctor on the region of the straight portion of the doctor. The supporting belt moves across the doctor in the direction of the arrow P.

I claim:

1. A device for applying glue to a supporting belt of a screen printing machine, comprising an interchangeable glue roller and a flexible doctor blade for wiping the excess glue from the supporting belt, the improvement consisting in that means are provided for adapting the operative length of the doctor blade to the desired width of the glue film upon said belt by turning both ends of the doctor blade towards the glue roller.

2. A device according to claim 1, comprising a holder, arranged substantially parallel to the glue roller, with a groove, delimited by ledges, into which fits an edge of the doctor blade, carriages which are slidable along the end parts of the holder, while at that location the groove is one one side delimited by a ledge and on the other side the carriages adjoin the groove by an inclined slit extending obliquely to the groove, the inclined slit having the same cross section as the groove and being turned towards the glue roller.

3. A device according to claim 2, wherein each extremity of the doctor blade is secured to a carriage.

4. A device according to claim 2 wherein the carriages are capable of being locked on the doctor holder. 

1. A device for applying glue to a supporting belt of a screen printing machine, comprising an interchangeable glue roller and a flexible doctor blade for wiping the excess glue from the supporting belt, the improvement consisting in that means are provided for adapting the operative length of the doctor blade to the desired width of the glue film upon said belt by turning both ends of the doctor blade towards the glue roller.
 2. A device according to claim 1, comprising a holder, arranged substantially parallel to the glue roller, with a groove, delimited by ledges, into which fits an edge of the doctor blade, carriages which are slidable along the end parts of the holder, while at that location the groove is one one side delimited by a ledge and on the other side the carriages adjoin the groove by an inclined slit extending obliquely to the groove, the inclined slit having the same cross section as the groove and being turned towards the glue roller.
 3. A device according to claim 2, wherein each extremity of the doctor blade is secured to a carriage.
 4. A device according to claim 2 wherein the carriages are capable of being locked on the doctor holder. 